Composite numbers k such that 2^(k-4) == 1 (mod k).

Terms

a(0) =4a(1) =40369a(2) =673663a(3) =990409a(4) =1697609a(5) =2073127a(6) =6462649a(7) =7527199a(8) =7559479a(9) =14421169a(10) =21484129a(11) =37825753a(12) =57233047a(13) =130647919a(14) =141735559a(15) =179203369a(16) =188967289a(17) =218206489a(18) =259195009a(19) =264538057a(20) =277628449a(21) =330662479a(22) =398321239a(23) =501126487a(24) =506958313a(25) =612368311a(26) =767983759